120
See also: William Gilbert 44 ■ Alessandro Volta 90–95 ■ Michael Faraday 121 ■
James Clerk Maxwell 180–85T
he quest to discover an
underlying unity to all
forces and matter is as old
as science itself, but the first big
break came in 1820, when the
Danish philosopher Hans Christian
Ørsted found a link between
magnetism and electricity. The link
had been suggested to him by the
German chemist and physicist
Johann Wilhelm Ritter, whom he
had met in 1801. Already influenced
by the philosopher Immanuel Kant’sidea that there is a unity to nature,
Ørsted now investigated the
possibility in earnest.Chance discovery
Lecturing at the University of
Copenhagen, Ørsted wanted to
show his students how the electric
current from a voltaic pile (the
battery invented by Alessandro
Volta in 1800) can heat up a wire
and make it glow. He noticed that a
compass needle standing near the
wire moved every time the current
was switched on. This was the first
proof of a link between electricity
and magnetism. Further study
convinced him that the current
produced a circular magnetic field
as it flowed through the wire.
Ørsted’s discovery rapidly
prompted scientists across Europe
to investigate electromagnetism.
Later that year, French physicist
André-Marie Ampère formulated
a mathematical theory for the
new phenomenon and, in 1821,
Michael Faraday demonstrated that
electromagnetic force could convert
electrical into mechanical energy. ■THE ELECTRIC
CONFLICT IS NOT
RESTRICTED TO THE
CONDUCTING WIRE
HANS CHRISTIAN ØRSTED (1777–1851)
IN CONTEXT
BRANCH
PhysicsBEFORE
1600 William Gilbert conducts
the first scientific experiments
on electricity and magnetism.1800 Alessandro Volta creates
the first electric battery.AFTER
1820 André-Marie Ampère
develops a mathematical
theory of electromagnetism.
1821 Michael Faraday is able
to show electromagnetic
rotation in action, by creating
the first electric motor.1831 Faraday and US scientist
Joseph Henry independently
discover electromagnetic
induction; Faraday uses it in
the first generator to convert
motion into electricity.1864 James Clerk Maxwell
formulates a set of equations
to describe electromagnetic
waves—including light waves.It appears that the electric
conflict is not restricted to the
conducting wire, but that it
has a rather extended sphere
of activity around it.
Hans Christian Ørsted